There are a lot of things going for the proposed extension of the MBTA Silver Line to Chelsea and East Boston.

The proposed route, which links the two neighborhoods with South Station, would connect two historically underserved communities to the heart of Boston. It would ease crowding on the notoriously overcrowded and plodding 111 bus line. And it would be a first step toward fulfilling transportation advocates’ goals of connecting the far reaches of the MBTA system in an “urban ring.”

But most of all, it’s cheap. The extension would cost somewhere on the order of tens of millions of dollars, according to officials with the Massachusetts Department of Transportation.

“In terms of transportation dollars,” said Jay Ash, Chelsea’s city manager, who has pushed for the extension for 17 years, “this is a relatively modest expenditure.”

As legislators get closer to passing a transportation finance package that will probably end up being more moderate than Governor Deval Patrick’s $1.1 billion proposal for new transportation revenue, hopes are waning that the state will have the money in coming years to fund big-budget rail projects, like a passenger train to Fall River and New Bedford.

Instead, the future may hold more smaller-scale projects like the extension of the Silver Line bus service, a proposal that is currently in the beginning stages of a nine-month community review. Residents and business representatives in Chelsea and East Boston were expected to gather Wednesday with MassDOT officials outlining the various routes the Silver Line extension could take and soliciting opinions from residents.

“The idea of being able to get to South Station very quickly and easily without having to make multiple connections is very attractive,” said Sharlene McLean, a longtime Chelsea resident.

What is also attractive, experts say, is the price. At a Tuesday presentation sponsored by the Urban Land Institute Boston Infrastructure Council, Michael Widmer, president of the Massachusetts Taxpayer Foundation, said he envisions that the State House’s smaller transportation funding package will mean that smaller-scale projects receive the most support in coming years.

Transportation planners must be ready to pitch more modest projects “so one isn’t asking for the moon,” Widmer said, “rather than laying out a huge unattainable price tag.”

Currently, Chelsea is accessible by buses, which are packed even at non-peak hours. And while the commuter rail makes a stop in Chelsea, “it’s not the type of thing that someone who’s really relying on transit is going to be able to use all the time” because it only stops once or twice per hour, said Scott Hamwey, project manager with MassDOT’s Office of Transportation Planning.

Parts of the proposed extension are certain: The new route would start at South Station, travel through the Seaport District, continue through the dedicated Silver Line portion of the Ted Williams Tunnel, and make a stop at Airport Station on the Blue Line, bypassing all the airport terminals.

From there, options open up: The route would most likely travel on a bypass road — which is currently open to taxis, trucks, and commercial vehicles — and onto the Chelsea Street Bridge, where renovations were just completed last year. After that, officials must decide whether to direct the route through downtown Chelsea on Central Avenue, alongside traffic, or pave over part of a train route already owned by MassDOT, which lies a few blocks from the center of town.

Ash said he would wait until MassDOT has completed a study on the potential impact of the Silver Line extension before making a decision on whether he would support the option that runs through the middle of town or the one that would hug an existing transit right-of-way.

But, he said, he was concerned that the Central Avenue option would be almost as slow as existing bus lines.

“In order for the service to be successful, it has to be bus rapid transit, and the ‘rapid’ is an important term,” Ash said. “It needs to get people in and out of Chelsea as quickly as possible.”

He continued: “That goal is more likely to be achieved if there’s a dedicated right-of-way.”

But some residents disagree. McLean, who lives on the Chelsea waterfront, said she believes it’s more important to bring the Silver Line buses into the heart of the city. For example, she said, if she’s headed to Logan International Airport, she would not drag her suitcase to a stop that is a 20-minute walk away.

“If they go that route, it’s not going to be in an area where people are going to use it — it’s not right in the most populated areas,” McLean said. “If it’s going to be on the other side of Chelsea, I’ll just use the buses to get to the train.”

Some, like state Senator Robert L. Hedlund, a Republican from Weymouth, question the wisdom of planning for an extension in the T system while the transit authority suffers from a crippling debt and lacks money to make repairs on the existing system.

“You may be serving a community that is more in need of transit options,” Hedlund said. “But you can’t keep taking on these new debts and building these new services.”

The future of the Silver Line bus route is also dependent on the fleet of buses themselves, hybrid diesel-electric vehicles that are due for a mid-life overhaul in the next several years. While repairs are made, there will not be enough buses to expand service on the Silver Line.

But officials are hesitant to buy more buses right now because diesel-electric vehicles are becoming outdated, as transit developers improve technology on all-electric buses.

Still, residents are hopeful that the Silver Line will bring new interest to the Chelsea community. Cultural amenities like the Apollinaire Theatre Company, the Chelsea Art Walk, and a growing cluster of high-end restaurants are sometimes overlooked, McLean said, because of the hassles of getting to the neighborhood.

“It’s not the South End — yet. People aren’t necessarily willing to go through a lot of effort to get there, and the Silver Line would make it easy,” McLean said.

“There’s still the idea that Chelsea is what it was 20 years ago, and it’s not,” she continued. That stereotype would change, she said, “if people knew that they could get there more easily, rather than having to take multiple connections.”